"Genocidal Organ" is a manga adaptation of Project Itoh's novel of the same name, illustrated by Sakaki Satoshi. Set in a near-future world, the narrative explores themes of global terrorism, state surveillance, and the manipulation of language and psychology. The story unfolds in a world where the United States has become a surveillance state following a series of devastating terrorist attacks, including the 9/11 incident and a subsequent nuclear detonation in Sarajevo. In response, the U.S. government has developed advanced surveillance technologies to monitor and preemptively eliminate potential threats.

The protagonist, Clavis Shepherd, is a covert operative working for a special forces unit tasked with tracking down and neutralizing high-value targets involved in orchestrating genocides across the globe. Clavis is a skilled and emotionally detached soldier, shaped by the brutal realities of his missions. His latest assignment leads him to John Paul, a mysterious American linguist and former intelligence officer believed to be the mastermind behind a series of genocidal conflicts. John Paul has developed a method to manipulate language and psychological triggers, effectively inducing mass violence and societal collapse in targeted regions.

As Clavis delves deeper into the mission, he uncovers the extent of John Paul's influence and the ethical dilemmas surrounding the use of psychological warfare. The narrative shifts between Clavis's present-day pursuit of John Paul and flashbacks that reveal the origins of John Paul's theories and experiments. These flashbacks provide insight into the moral ambiguity of both the protagonist and antagonist, blurring the lines between hero and villain.

The story also introduces Lucia Sukrova, a former child soldier and survivor of one of the genocides orchestrated by John Paul. Lucia becomes a key figure in Clavis's mission, offering a human perspective on the devastating consequences of John Paul's actions. Her presence challenges Clavis's detachment and forces him to confront the emotional and moral weight of his work.

The plot builds toward a climactic confrontation between Clavis and John Paul, where the true nature of the "genocidal organ"—a metaphorical concept representing the mechanisms of societal breakdown—is revealed. The resolution raises questions about the cost of security, the ethics of preemptive violence, and the power of language to shape human behavior. The manga concludes with a reflection on the cyclical nature of violence and the enduring impact of psychological manipulation on global stability.